If a man is getting deepthroated and he does not let the headgiver know when he is about to cum and, thereby spontaneously combusts a load of semen into the back of her throat so that she gags and sometimes asphyxiates herself, he is said to have "given her the cough syrup" or "a taste of her own medicine"
John was an agog tennis player. After he lost a painful match to a handicapped black guy he went home to his normally fawning wife. She was upset that he hadn't won his match so she wasn't willing to chug his cum conduit. Suddenly he forced her head down and made sure it went all the way down her throat, then he gave her the cough syrup, she was taken in an ambulance to the ER, and she died the next day due to internal bleeding.